Serena Williams shows off post-baby weight loss as she slips back into jean shorts 2 weeks after giving birth

Day-Um, Mama! Serena Williams showed she’s serious about getting back into shape and back on the court on Saturday. The 35-year-old tennis pro shared a mirror selfie of her impressive post-baby body on Snapchat.

“Biceps,” the caption for one post reads. The photo features baby Alexis with her arms up in a onesie that reads, “Smart and Strong like my Mama.”

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Shocking celebrity weight-loss transformations

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Shocking celebrity weight-loss transformations

Mama June in 2017

The "Honey Boo Boo" star documented her weight loss journey on her very own reality show! She is now down to a size 4 -- and she looks incredible!

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Mama June in 2013

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Khloe Kardashian in 2012

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Khloe Kardashian in 2016

Hard work does pay off! The youngest Kardashian sister is obsessed with exercising and documents all her workout sessions on social media.

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Lena Dunham in 2015

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Lena Dunham in 2017

The "Girls" star lost a significant amount of weight after going on a holistic diet to help alleviate symptoms of endometriosis.

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Wendy Williams in 2012

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Wendy Williams in 2017

The TV personality revealed in 2015 that she lost 50 pounds over the course of three years with a healthy diet that doesn't include refined sugars, meat, dairy or "eating after dark." It looks like she's been committed to the strict diet. She looks better than ever in 2017!

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Ricki Lake in 2010

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Ricki Lake in 2011

The actress lost 20 pounds when she appeared on "Dancing With the Stars" in 2011.

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Jordin Sparks in 2008

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Jordin Sparks in 2017

Hard work pays off! "American Idol" alum began her weight loss journey by walking around her neighborhood and the rest was history! Her favorite workout? Zumba.

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Sara Rue in 2003

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Sara Rue in 2016

The "Rules of Engagement" star is a total fan of Jenny Craig for its simplicity. She looks incredible and totally glowing!

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Jonah Hill in 2014

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Jonah Hill in 2017

Talk about a transformation! Hill has lost weight and gained weight through the years -- depending on the movie he's working on -- but his latest transformation is absolutely jaw-dropping.

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Christina Aguilera in 2012

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Christina Aguilera in 2013

Smoke show! The songstress dropped 20 pounds over the course of one year. Doesn't she look incredible?!

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Miranda Lambert in 2012

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Miranda Lambert in 2013

The country crooner slammed critics who accused her of having weight loss surgery. She revealed that she dropped the pounds the old-fashioned way -- eating right and working out with her trainer!